What does It's from "The Goldbergs". Barry says, "Everything I do in this costume fights my agenda." What does "fights my agenda" mean? mean?

See a translation

Your agenda means basically what you stand for (technically it means what you hope to accomplish)
It could be synonymous with purpose maybe. If someone has a “hidden agenda” it means they have things they are doing things (working toward accomplishing) in secret. For example, he appeared to be harmlessly inviting him to dinner, but in reality he had a secret agenda: to weasel information out of him.

Anyways, to paraphrase: Everything I do in this costume goes against what I stand for/what I strive to accomplish (whether it be a message, a goal, a task etc)